Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
H,W = map(int, input().split())
S = [input() for i in range(H)]
queue = [(0,0,1)]
done ={(0,0)}
count = sum(row.count("#") for row in S)

def bfs(x,y,c):
    if(x<0 or y<0 or x>=W or y>=H or S[y][x]=="#"):
        return
    
    if(x,y) in done:
        return
    
    queue.append((x,y,c+1))
    done.add((x,y))

dx = [1,-1,0,0]
dy = [0,0,1,-1] 
flag= -1
while queue:
    x,y,c = queue.pop(0)
    if x==W-1 and y==H-1:
        flag=1
        break
    for i in range(4):
        bfs(x+dx[i],y+dy[i],c)

print(flag if flag == -1 else (H*W-count-c))